dna – october 5, 2010 1.what do we mean when we talk about the trophic structure of a community?...
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DNA – October 5, 2010
1. What do we mean when we talk about the trophic structure of a community?
2. What’s the difference between an autotroph and a heterotroph?
3. What is ALWAYS going to be at the top of the food chain/food web? Why?
4. Why is there a limit to the # of links in a food chain?
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Influential Species in Communities
Ms. KlinkhachornOctober 5, 2010
AP Biology
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Dominant Species
• Most abundant species in a community– Community: 50A, 10B, 5C, 5D, 15, E, 15F
• Have a lot of control over the distribution of other species– Example: If a maple tree is your dominant species,
it affects abiotic factors like shade and soil nutrients. This shade and soil composition affect the other species that can grow there
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Why do species become dominant?
• Have a competitive advantage• Good at avoiding predation or disease– Example: invasive species (not native)
• Think about what happens when you remove a dominant species from a community
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Keystone Species
• Don’t have to have a high abundance, but have a strong control because of their niches– Removal of a keystone species would affect the
species richness of an area
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Foundation Species (Engineers)• These species physically
change the environment– Example: Beaver
• Also called facilitators because they have positive effects on other species– Example:
• Black-needle rush (a plant)
• Prairie Dog